“The learning curve for lung cancer screening cannot be underestimated,” James L. Mulshine, MD, director of Rush Translational Sciences Consortium at Rush Medical College in Chicago, told Health Imaging. Given the massive learning curve, it can be helpful to survey the clinical landscape and see what lessons it holds.

This feature is the first in a web series focused on the details of lung cancer screening programs. Look for additional features on upcoming Mondays in Health Imaging.

Uncharted territory

For the last few decades, physicians have grappled with a fairly familiar natural history for many lung cancer patients. Diagnosis and management for the long-term smoker who presented coughing up blood followed a straightforward path.

However, CT screening changes the workup. “The International-Early Lung Cancer Action Program (I-ELCAP) and Nederlands-Leuvens Longkanker Screenings Onderzoek (NELSON) trial helped physicians understand that we are involved in the natural history of lung cancer at a much earlier state than in the routine symptomatic patient,” said Mulshine.

The patient is typically asymptomatic and healthy. “We need to train a new generation of providers in the ethos of screening as opposed to the treatment of advanced disease,” explained Mulshine.

However, cancer screening is not a completely foreign concept. Lung cancer screening is characterized by some dynamics that parallel breast cancer screening. For example, researchers are trying to determine the optimal surgical intervention for screen-detected lung cancer: limited resection with video-assisted thoracic surgery or a standard open procedure. It may follow the path of surgical treatment for breast cancer, which has evolved from aggressive mastectomies to more tailored, less invasive surgical interventions.

“This is related to screening mammography, which detects smaller breast cancers and greatly diminishes the need for radical surgeries. The need to diminish side effects [in the healthy patient with a screen-detected nodule] becomes much more important,” said Mulshine.

Communication and education has proved challenging for screening mammography, particularly in the wake of the U.S. Preventive Services Task Force (USPSTF) revision of recommendations for screening mammography in November 2009. The recommendations of most women’s health organizations diverge from those of the USPSTF.

Lung cancer screening guidelines and recommendations are just beginning to emerge, and most primary care providers see few lung cancer patients annually. “The challenge is to educate the public, healthcare workers and primary care physicians, so the transmission of information is more consistent,” said Mulshine.

However, the paths of the lung cancer screening programs are likely to diverge from breast cancer in key ways, continued Mulshine.

A good screening mammography program misses 20 to 25 percent of primary breast cancers. In contrast, in a good CT lung cancer screening program, the false-negative rate drops to a single digit because CT imaging of the lung provides clear visualization of the early stage of disease.

In addition, screening mammographers have continued to encounter questions of overdiagnosis. CT screening for lung cancer, however, offers a filter for overdiagnosis. Physicians can image the patient over time to determine if a nodule is growing rapidly. This allows physicians to more effectively differentiate between clinically aggressive and clinically indolent cases, which helps mitigate overdiagnosis, said Mulshine.

The final key difference between lung and breast cancer screening relates to the screening population. Screening mammography is targeted to a large pool of women ages 40 and older. Lung cancer screening is targeted to adults 55 years and older with a smoking history. “It’s a much smaller patient pool that is enriched for positive findings because tobacco exposure is such a powerful risk factor for the development of lung cancer.”

Cardiac bypass surgery offers another model for lung cancer screening programs. Bypass programs are held to a threshold of excellence; otherwise the service line is not offered. Lung cancer screening programs need to follow that model, said Mulshine, which requires programs to share outcomes. “It’s important that institutions commit to doing screening with transparency and accountability.”

For more about best practices in lung cancer screening, please read ACS on lung cancer screening: Conversation, caution, then CT, maybe, and RSNA: Lung cancer screening—where hope and fear converge.